Hydrothermal synthesis of vanadate/phosphate hydroxyapatite solid solutions

A series of vanadate substituted hydroxyapatite was directly prepared by a simple hydrothermal method at low temperature (110–200 °C) in NaOH solutions for 14 h. The apatite samples were characterized by powder X-ray diffraction, ICP chemical analysis, nitrogen physisorption, TEM, and FTIR measurements. The vanadate/phosphate hydroxyapatite solid solution, i.e., Ca10(VO4)x(PO4)6−x(OH)2 (xεI=0, 1, 2, 3, 4, 5, and 6), had a single phase of apatite structure. The lattice parameters increased linearly with increasing V content (x) with obeying the Vegard's law. All Ca10(VO4)x(PO4)6−x(OH)2 (x=I) samples showed the OH vibration band around 3560 cm−1. The white apatite samples were column crystals with length of about 40–100 nm and width of about 25–40 nm.